Related papers: Diphoton signals for Low Scale Gravity in Extra Di…
We consider graviton-induced Bremsstrahlung at future e^+e^- colliders in both the ADD and RS models, with emphasis on the photon perpendicular momentum and angular distribution. The photon spectrum is shown to be harder than in the…
After a lightning review of current bounds on the masses of supersymmetric particles, we describe strategies that may be helpful for extracting signals from the production of squarks, gluinos or top squarks, and from associated…
The potential of triphoton production to obtain limits on anomalous Higgs boson couplings at $H\gamma\gamma$ and $HZ\gamma$ vertices is studied in Standard Model Effective Field Theory (EFT) framework for the post-LHC circular high-energy…
Light-by-light scatterings contain rich information on the photon coupling to virtual and real particle states. In the context of quantum electrodynamics (QED), photons can couple to a virtual $e^+e^-$ pair. Photons may also couple to known…
Many scenarios of physics beyond the Standard Model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional scalars with masses in the MeV to GeV…
Recently, an excess of events in diphoton channel with invariant mass of about 750 GeV has been reported by the ATLAS and CMS Collaborations. Considering it as a tantalizing hint for new physics beyond the Standard Model (SM), we propose a…
We consider the effects of heavy Majorana neutrinos N with sub-TeV masses. We argue that the mere presence of these particles would be a signal of physics beyond the minimal seesaw mechanism and their interactions are, therefore, best…
The production of photon pairs in $e^+e^-\rightarrow f \bar f \gamma\gamma$ processes is studied using exact helicity amplitudes at tree level. Total cross sections, including initial state radiation effects, are given. They are presented…
We present a study of photon-photon scattering for $W_{\gamma\gamma} < 5$ GeV. We extend earlier calculations of this cross section for $W_{\gamma\gamma}>$ 5 GeV into the low mass range where photoproduction of the pseudoscalar mesons…
In central collisions at relativistic heavy ion colliders like the Relativistic Heavy Ion Collider RHIC/Brookhaven and the Large Hadron Collider LHC (in its heavy ion mode) at CERN/Geneva, one aims at detecting a new form of hadronic matter…
Due to coherence, there are strong electromagnetic fields of short duration in very peripheral collisions. They give rise to photon-photon and photon-nucleus collisions with a high flux up to an invariant mass region hitherto unexplored…
We have performed a search for new particles which decay to two photons using 1.2/fb of integrated luminosity from p-pbar collisions at sqrt(s) = 1.96 TeV collected using the CDF II Detector at the Fermilab Tevatron. We find the diphoton…
We study $\eta$ photoproduction off the deuteron ($\gamma d\to\eta pn$) at a special kinematics: $\sim 0.94$ GeV of the photon beam energy and $\sim 0^\circ$ of the scattering angle of the proton. This kinematics is ideal to extract the…
The process e+e- to gamma gamma (gamma) is studied using data recorded with the OPAL detector at LEP. The data sample corresponds to a total integrated luminosity of 56.2 pb-1 taken at a centre-of-mass energy of 183 GeV. The measured…
Elastic light-by-light scattering, $\gamma\gamma\to\gamma\gamma$, is open to study at the Large Hadron Collider thanks to the large quasi-real photon fluxes available in electromagnetic interactions of protons (p) and lead (Pb) ions. The…
Single and multi-photon events with missing energy are analysed using data collected with the L3 detector at LEP at a centre-of-mass energy of 189 GeV, for a total of 176 pb^{-1} of integrated luminosity. The cross section of the process…
We consider minimal effective interactions of the 750 GeV mass resonance observed recently by ATLAS and CMS. Assuming a new scalar and gauge invariant effective interactions leads to non-trivial two particle scattering amplitudes with…
Recently, a scenario has been proposed in which the gravitational scale could be as low as the TeV scale, and extra dimensions could be large and detectable at the electroweak scale. Although supersymmetry is not a requirement of this…
The dark photon is a new gauge boson which arises from an extra U'(1) gauge symmetry. In this paper, a novel dark photon production mechanism based on MeV-scale $\gamma$-$\gamma$ collider is considered: $\gamma \gamma \rightarrow \gamma…
The level of sensitivity of the processes $\gamma\gamma \to ZZ$, $\gamma\gamma \to W^+W^-$ and $\gamma\gamma \to t\bar t$ to the Higgs sector of the Standard Model Lagrangian in the energy region between 200 GeV and 1 TeV is examined. The…